This invention relates generally to electric motors, and more particularly to a stator frame for an electric motor.
Electric motors generate heat during operation as a result of both electrical and mechanical losses, and these motors typically are cooled for efficient operation of the motor. An excessively high motor temperature may result in motor bearing failure or damage to stator winding insulation.
Electric motors generally have an enclosure, or housing, that includes a frame and endshields. Two types of enclosures are xe2x80x9copenxe2x80x9d and xe2x80x9ctotally enclosed.xe2x80x9d Motors that include totally enclosed type enclosures are typically used in applications including airborne contaminants, e.g., dirt, oil, or mist. Both convection type cooling and conduction type cooling occurs within the enclosure, and some form of convection cooling occurs at the external surfaces of the enclosure. At least some known totally enclosed motor enclosures are liquid cooled and the motor enclosure is connected to a coolant supply that is in flow communication with a cooling circuit. The liquid coolant could, for example, be water, hydraulic oil, or other relatively low temperature process liquids.
In at least some known totally enclosed liquid cooled motor configurations, the stator frame includes a cooling passageway through which a cooling medium is directed to facilitate removing heat generated by the motor. The cooling passageway may include a cooling conduit. The cooling conduit is formed by welding tubing and stabilizing bars in a desired geometric configuration. Because of extensive welding and supplies, such motors are typically more expensive to fabricate than air cooled motors. Furthermore, because the cooling conduit includes a plurality of welds, liquid cooled motors are susceptible to corrosion and to liquid leaks. As corrosion builds-up within the cooling passageway over time, the overall heat transfer capability of the liquid cooled motor may degrade.
In one aspect, a stator frame is provided for an electric motor. The frame includes a substantially cylindrical shaped body section having opposed ends, a cooling passageway extending through at least a portion of the body section, and at least one spacer bar. The cooling passageway includes a cooling conduit having an inlet port and an outlet port in flow communication with the cooling passageway. The spacer bar has a notched side and at least one finger extending therefrom such that the finger mechanically couples the spacer bar to the cooling conduit.
In another aspect, an electric motor is provided having a stator frame including a substantially cylindrical shaped body section having opposed first and second ends, a cooling passageway extending through at least a portion of said body section, and at least one spacer bar. The first stator frame end having a first end shield secured thereto, and the second stator frame end having a second end shield secured thereto. The cooling passageway includes a cooling conduit having an inlet port and an outlet port in flow communication with the cooling passageway. The spacer bar has a notched side and at least one finger extending therefrom such that the finger mechanically couples the spacer bar to the cooling conduit.
In another aspect, a method is provided for fabricating a stator frame for an electric motor. The method includes arranging a cooling conduit into a selected configuration, mechanically coupling a spacer bar including a notched side to the cooling conduit, and securing the spacer bar to the cooling conduit by mechanically coupling at least one finger projecting outwardly from the spacer bar to the cooling conduit.